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Original question:

TPS61163A: Duty input resolution

TPS61163A: Minimum IFBx current(accuracy) that we can guarantee in datasheet

Roy Chou1
Genius 13045 points
Part Number: TPS61163A

Hi Team,

I asked a similar question before. https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1252784/tps61163a-duty-input-resolution/4755790#4755790

And below is our condition.

  •  IFBx = 1.229V/615k*1030 = 2.05832mA
  • 1wire, 16 -> 2.05832*16/511 = 64uA = IFBx (IFB1+IFB2 = 128uA)

Below is the 124pcs histogram that we measured in above condition. The range is wide.

We would like to check with you about below items.

  1. Do we have spec for minimum IFBx current include 9bit One-Wire Digital Interface?
  2. What is our minimum IFBx current can be guaranteed(100% duty, 1 1111 1111)?

Regards,

Roy

  • 0
    TI__Mastermind 22840 points

    Hi Roy,

    We only have the current accuracy data when ISET=20uA, and the accuracy is also within the range as datasheet listed.

    BR

    Patrick

  • 0 in reply to Patrick Yao
    TI__Genius 13045 points

    Hi Patrick,

    According to your statement, I find it in datasheet.

    But in above test result, the average current should be within in 128uA +/-2%. (0-70C)

    Do we have accuracy about the duty (<100%)?

    Regards,

    Roy

  • 0 in reply to Roy Chou1
    TI__Mastermind 22840 points

    Hi Roy,

    For analog dimming, usually the current accuracy is low when the current is small. But we don't have test data of the ILED=128uA. Please note that the I_ISET is not the ILED. There is a constant in formula as well.

    BR

    Patrick

  • 0 in reply to Patrick Yao
    TI__Genius 13045 points

    Hi Patrick,

    The analog dimming, I think ii means the RISET. In datasheet we guarantee the IFB_Full accuracy = +/-2% when IFB_Full down to 20uA.

    Or do you mean that the "20uA" here isn't IFBx? If so, what does it mean?

    1. Does TI only guarantee the spec of IFB_full when D = 100%.

                

    2. What is the accuracy spec for One-Wire Digital Interface (EasyScale Interface)? Current issue is that customer found that the current difference is large in low duty.

    3. The new issue is that

    - If our 50% duty current that we measured in the beginning was 19.079mA and then we set the lower duty like 10% and then back to 50% duty. The current became 18.416mA. But when we tried to enlarge the duty from 50% to 60% and then back to 50%. It will back to 19.079mA. (50% is an example, the issue can be duplicated when duty is from high to low and then to high.)

    We can a webex meeting directly if you have any question. 

    Regards,

    Roy

  • 0 in reply to Roy Chou1
    TI__Mastermind 22840 points

    Hi Roy,

    Per talked, I will setup the EVM test.

    BR

    Patrick